At present, a rechargeable electronic cigarette and an electronic cigarette case for charging contained electronic cigarette are not provided with a circuit for preventing a charging power supply from reversely connecting. If there were no circuit for preventing a charging power supply from reversely connecting, it would face a risk while the electronic cigarette or the electronic cigarette case is charged by the charging power supply through an adapter. Now, there is no uniform criterion for the adapter. The core heads of some adapters are anode, and the core heads of other adapters are cathode. If the core head of the adapter charging the electronic cigarette or the electronic cigarette case is cathode, it would damage charging circuit and battery, and cause short-circuit, explosion, even fire accident and so on.